Electromagnetic Induction: Faraday's Law and Its Applications

Question 1

According to Faraday's law, the magnitude of the induced EMF in a coil is directly proportional to:

Accepted Answer

The rate of change of magnetic flux through the coil

Answer

The number of turns in the coil

Answer

The area of the coil

Answer

The resistance of the coil

Question 2

Which of the following is NOT an application of Faraday's law?

Accepted Answer

Capacitors

Answer

Electric generators

Answer

Electric motors

Answer

Transformers

Question 3

Which of the following materials is NOT suitable for use as a core in an inductor?

Accepted Answer

Copper

Answer

Iron

Answer

Steel

Answer

Nickel

Question 4

A transformer has a primary winding with 100 turns and a secondary winding with 200 turns. If the voltage across the primary winding is 120 V, what is the voltage across the secondary winding?

Accepted Answer

240 V

Answer

60 V

Answer

120 V

Answer

480 V

Question 5

Faraday's Law states that the electromotive force (EMF) induced in a loop of wire is proportional to what?

Accepted Answer

Rate of change of magnetic flux linked with the loop

Answer

Area of the loop

Answer

Change in magnetic flux

Answer

Magnetic field strength

Question 6

Which of the following statements correctly describes Lenz's law?

Accepted Answer

The direction of the induced electromotive force (EMF) opposes the change in magnetic flux.

Answer

The direction of the induced EMF enhances the change in magnetic flux.

Answer

The direction of the induced EMF is perpendicular to the change in magnetic flux.

Answer

The direction of the induced EMF is parallel to the change in magnetic flux.

Question 7

Which of the following factors does NOT affect the magnitude of the induced EMF?

Accepted Answer

Number of turns in the coil

Answer

Rate of change of magnetic flux

Answer

Area of the conductor loop

Answer

Orientation of the conductor loop

Question 8

Which of the following devices operates on the principle of Faraday's law?

Accepted Answer

Transformer

Answer

Capacitor

Answer

Inductor

Answer

Resistor

Question 9

Which of the following is NOT a factor affecting the magnitude of the electromotive force (EMF) induced in a conductor?

Accepted Answer

Resistance of the conductor

Answer

Rate of change of magnetic flux

Answer

Area of the conductor loop

Answer

Angle between the conductor loop and the magnetic field

Question 10

When a switch is closed, connecting a solenoid to a battery, what happens to the magnetic field inside the solenoid?

Accepted Answer

It increases

Answer

It decreases

Answer

It reverses direction

Answer

It remains constant

Question 11

How does an electric generator utilize Faraday's law of electromagnetic induction to convert mechanical energy into electrical energy?

Accepted Answer

An electric generator converts mechanical energy into electrical energy by rotating a coil within a magnetic field.

Answer

Faraday's law is not applicable to the design of electric generators.

Answer

An electric generator produces a constant voltage regardless of its rotational speed.

Answer

The direction of the induced EMF in a generator is solely determined by Lenz's law.

Question 12

If the magnetic field strength increases from 4 T to 8 T, how will the magnitude of the induced EMF in a conductor change, assuming the rate of change of magnetic flux remains constant?

Accepted Answer

Double

Answer

No change

Answer

Halve

Answer

Quadruple

Question 13

According to Faraday's law, what induces an electromotive force (EMF) in a conductor?

Accepted Answer

Change in magnetic field through the conductor

Answer

Movement of the conductor through a magnetic field

Answer

Connection of the conductor to a battery

Answer

Exposure of the conductor to light

Question 14

Transformers transfer electrical energy from one circuit to another primarily through:

Accepted Answer

Mutual induction between coils

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 15

An inductor resists changes in current flow primarily by:

Accepted Answer

Storing energy in a magnetic field

Answer

Dissipating energy as heat

Answer

Generating an electric field

Answer

Reducing voltage

Question 16

The energy stored in an inductor is given by:

Accepted Answer

1/2 * L * I^2

Answer

L * I

Answer

1/2 * C * V^2

Answer

C * V

Question 17

According to Faraday's law, the mathematical expression for the electromotive force (EMF) induced in a conductor due to a changing magnetic flux is:

Accepted Answer

EMF = - (dΦ_B/dt)

Answer

EMF = (dΦ_B/dt)

Question 18

What is the SI unit of magnetic flux?

Accepted Answer

Weber

Question 19

According to Lenz's law, what determines the direction of the induced EMF?

Accepted Answer

It opposes the change in magnetic flux

Answer

It enhances the change in magnetic flux

Answer

It is perpendicular to the change in magnetic flux

Answer

It is parallel to the change in magnetic flux

Question 20

A conducting loop experiences a time-varying magnetic field. What is directly proportional to the induced EMF in the loop?

Accepted Answer

The magnetic flux through the loop

Answer

The area of the loop

Answer

The resistance of the loop

Answer

The strength of the magnetic field

Question 21

When a rectangular coil of wire rotates in a uniform magnetic field, what orientation of the coil's plane maximizes the induced EMF?

Accepted Answer

Perpendicular to the magnetic field

Answer

Parallel to the magnetic field

Answer

At an angle of 45 degrees to the magnetic field

Answer

At an angle of 60 degrees to the magnetic field

Question 22

An inductor stores energy in which field?

Accepted Answer

Magnetic field

Answer

Electric field

Answer

Gravitational field

Answer

Mechanical field

Question 23

What is the SI unit of inductance?

Accepted Answer

Henries

Answer

Farads

Answer

Ohms

Answer

Teslas

Question 24

Lenz's law states that the direction of the induced EMF is:

Accepted Answer

Such that the magnetic field produced by the induced current opposes the change in magnetic flux

Answer

Parallel to the direction of the magnetic field

Answer

Perpendicular to the direction of the magnetic field

Question 25

The induced EMF in a conductor is proportional to the rate of change of which of the following:

Accepted Answer

Magnetic flux

Answer

Gravitational field

Answer

Electric field

Answer

Temperature

Question 26

A conducting rod is moved perpendicularly through a magnetic field. The induced EMF in the rod is:

Accepted Answer

Proportional to the length of the rod and its velocity

Answer

Proportional only to the length of the rod

Answer

Proportional only to its velocity

Question 27

According to Faraday's law of electromagnetic induction, the induced EMF in a conductor depends on all of the following factors EXCEPT:

Accepted Answer

Resistance of the conductor

Answer

Area of the conductor loop

Answer

Rate of change of magnetic flux

Answer

Orientation of the conductor loop

Question 28

Faraday's law of electromagnetic induction states that the induced EMF in a conductor is equal to:

Accepted Answer

-dΦ/dt

Answer

ΔΦ/Δt

Answer

dΦ/dt

Answer

-ΔΦ/Δt

Question 29

The energy stored in an inductor is given by:

Accepted Answer

1/2LI^2

Answer

LI

Answer

L^2I

Answer

1/2LI

Question 30

A coil of wire is placed in a changing magnetic field. According to Faraday's Law, what will be induced in the coil?

Accepted Answer

Electromotive force (EMF)

Answer

Magnetic field

Answer

Electric current

Answer

Electrostatic charge

Question 31

Which of the following devices is a direct application of Faraday's Law?

Accepted Answer

Transformers

Answer

Radioactivity detectors

Answer

Capacitors

Answer

Electrolytic cells

Question 32

According to Lenz's Law, the direction of the induced EMF is such that it opposes what?

Accepted Answer

The change in magnetic flux

Answer

The movement of the coil

Answer

The direction of the magnetic field

Answer

The flow of current

Question 33

What is the unit of magnetic flux?

Accepted Answer

Weber (Wb)

Answer

Tesla (T)

Answer

Ampere (A)

Answer

Volt (V)

Question 34

Faraday's Law is used to explain the operation of which of the following devices?

Accepted Answer

Electric motors and generators

Answer

Batteries and fuel cells

Answer

Transistors and diodes

Answer

Capacitors and inductors

Question 35

Which law is used to determine the direction of the induced EMF?

Accepted Answer

Lenz's Law

Answer

Faraday's Law

Answer

Kirchhoff's Laws

Answer

Ohm's Law

Question 36

Which of the following accurately describes Faraday's law?

Accepted Answer

A changing magnetic field induces an electromotive force (EMF) in a nearby conductor; the EMF opposes this change.

Answer

A changing electric field induces an electromotive force (EMF) in a nearby conductor; the EMF supports this change.

Answer

A changing magnetic field induces a current in a nearby conductor.

Question 37

According to Lenz's law, the direction of the induced EMF is:

Accepted Answer

Always to oppose the change in magnetic flux

Answer

Parallel to the change in magnetic flux

Answer

Perpendicular to the change in magnetic flux

Answer

To support the change in magnetic flux

Question 38

Which factor increases the magnitude of the induced EMF in a conductor?

Accepted Answer

Increasing the rate of change of magnetic flux

Answer

Changing the shape of the coil

Answer

Increasing the resistance of the coil

Answer

Decreasing the number of turns in the coil

Question 39

A current-carrying wire experiences a force when placed in a magnetic field. What determines the magnitude of the force per unit length?

Accepted Answer

The current, the magnetic field strength, and the orientation of the wire to the field

Answer

Only the current and the length of the wire

Answer

Only the current and the magnetic field strength

Answer

Only the length of the wire and the magnetic field strength

Question 40

How does the induced EMF in an AC generator change when the frequency of the AC supply is increased?

Accepted Answer

It increases

Answer

It alternates

Answer

It decreases

Answer

It remains the same

Question 41

Which device relies on Faraday's law as its operating principle?

Accepted Answer

Transformer

Answer

Diode

Answer

Resistor

Answer

Capacitor

Question 42

What happens to the induced EMF in a rectangular loop of wire as it is rotated about an axis parallel to a magnetic field?

Accepted Answer

It alternates in polarity

Answer

It remains constant

Answer

It decreases

Answer

It increases

Question 43

Which material is unsuitable for use as a core in an inductor?

Accepted Answer

Aluminum

Answer

Steel

Answer

Iron

Question 44

What is the relationship between the induced EMF in a conducting loop and the rate of change of magnetic flux through the loop?

Accepted Answer

The induced EMF is directly proportional to the rate of change of magnetic flux.

Answer

The induced EMF is inversely proportional to the rate of change of magnetic flux.

Answer

The induced EMF is equal to the rate of change of magnetic flux.

Question 45

What occurs when the current in a coil wrapped around an iron core is suddenly decreased?

Accepted Answer

The magnetic field collapses, inducing an EMF in the coil.

Answer

The magnetic field remains constant.

Answer

The magnetic field reverses direction.

Answer

The magnetic field increases.

Question 46

A metal rod is moved through a magnetic field at a constant speed. What is the direction of the induced EMF?

Accepted Answer

Perpendicular to both the magnetic field and the direction of motion.

Answer

Parallel to the magnetic field.

Answer

Parallel to the direction of motion.

Question 47

A transformer is used to convert AC voltage from one voltage level to another. What is the principle of operation of a transformer?

Accepted Answer

Faraday's law of electromagnetic induction.

Answer

Kirchhoff's laws.

Answer

Ohm's law.

Answer

Ampere's law.

Question 48

A coil of wire is connected to a galvanometer. The coil is placed in a magnetic field and the field is suddenly increased. What will the galvanometer reading be?

Accepted Answer

A momentary deflection.

Answer

A deflection that increases with time.

Answer

Zero.

Answer

A steady deflection.

Question 49

A conducting loop is rotated in a magnetic field. The loop is perpendicular to the field and the rotation is at a constant speed. What is the shape of the graph of induced EMF versus time?

Accepted Answer

A cosine wave.

Answer

A circle.

Answer

A parabola.

Answer

A sine wave.

Question 50

A coil of wire is connected to a battery and a switch. When the switch is closed, the current in the coil increases. What is the direction of the induced EMF?

Accepted Answer

It opposes the change in current.

Answer

It is zero.

Answer

It is random.

Answer

It assists the change in current.